package limits

import "errors"

// Default mail body and attachment size limits (bytes unless noted).
const (
	MaxBodyFieldBytes                  = 4 << 20  // 4 MiB per body_text / body_html field
	MaxSendRequestBodyBytes            = 5 << 20  // 5 MiB JSON send/draft request
	MaxAttachmentBytes                 = 25 << 20 // 25 MiB per attachment file
	MaxMultipartUploadBytes            = 26 << 20 // 26 MiB multipart form (file + fields)
	MaxAttachmentsPerMessage           = 50
	MaxTotalAttachmentsPerMessageBytes = 100 << 20 // 100 MiB combined per message/draft
)

var (
	ErrAttachmentTooLarge       = errors.New("attachment too large")
	ErrTooManyAttachments       = errors.New("too many attachments")
	ErrAttachmentsTotalTooLarge = errors.New("attachments total size exceeded")
)

// ValidateAttachmentSize rejects a single attachment larger than MaxAttachmentBytes.
func ValidateAttachmentSize(size int64) error {
	if size > MaxAttachmentBytes {
		return ErrAttachmentTooLarge
	}
	return nil
}

// ValidateAttachmentQuota rejects when adding newSize would exceed per-message count or total size limits.
func ValidateAttachmentQuota(existingCount int, existingTotalBytes int64, newSize int64) error {
	if existingCount >= MaxAttachmentsPerMessage {
		return ErrTooManyAttachments
	}
	if existingTotalBytes+newSize > MaxTotalAttachmentsPerMessageBytes {
		return ErrAttachmentsTotalTooLarge
	}
	return nil
}